1. Field of the Invention
The present invention relates generally to seat adjusters of the type commonly used in motor vehicles and, more particularly, to a low profile seat adjuster providing vertical as well as fore-aft adjustment.
2. Description of Related Art
The automotive vehicle designer seeks to achieve an aerodynamic profile to satisfy fuel consumption goals as well as to provide an aesthetically appealing appearance. A low roof line is essential to achieving an aerodynamic profile. A vehicle having a low roof line must also provide adequate head room for a vehicle occupant. Therefore, a low vertical profile seat must be utilized. The vertical profile of a seat is dictated by the height of the mechanism which provides vertical as well as fore-aft positional adjustment. Conventional technology such as described in U.S. Pat. Nos. Tanaka 3,182,947 and Colautti, et al. 4,509,382 feature telescoping devices which include telescoping segments, which present an objectionably tall profile when adjusted to minimum vertical height position.
An additional problem encountered in seeking a seat design offering a minimum vertical profile is presented by mechanisms seeking to achieve fore-aft positioning of a vehicle seat. Such mechanisms present an overall height which is an accumulation of the individual heights of the transmission and the tracks. For example, in Aihara, et al. U.S. Pat. No. 4,805,866, the transmission is located above and coaxial with the tracks. Therefore, the minimum profile defined by a seat adjusted to minimum vertical elevation is restricted by the height of the transmission protruding above the tracks themselves. Alternatively, the transmission may be located within the track. Such an implementation, however, requires an enlarged track cross section which significantly adds to the height thereof. The minimum profile defined by a seat adjusted to minimum vertical elevation is restricted by the height of the enlarged track. Therefore, there is a need to provide vertical height adjustment as well as fore-aft seat positioning mechanisms which will provide a minimum profile to permit use of a low profile seat.